Ethylene-propylene terpolymer and crystalline 1,2 polybutadiene

ABSTRACT

An ethylene-propylene rubber composition comprising 3 to 50 % by weight of at least one 1,2-polybutadiene having a 1,2-addition unit content of at least 70 %, a crystallinity of at least 5 % and an intrinsic viscosity ( Eta ) as measured in toluene at 30*C of at least 0.7 dl/g, and 97 to 50 % by weight of at least one ethylene-propylene-diene terpolymer. The above composition has a high vulcanization rate, a high green strength and an excellent processability.

United States Patent n91 Yaeda et al.

l ETHYLENE-PROPYLENE TERPOLYMER AND CRYSTALLINE 1,2 POLYBUTADIENE [75] lnventors: Yasuyuki Yaeda; Yoshishige Chikatsu; Noriaki Ando, all of Yokkaichi; Ryuichi Sakata, Kobe, all of Japan [73] Assignee: Japan Synthetic Rubber Co.,

Limited. Tokyo. Japan [22] Filed: Dec. ll, 1973 121] App]. No.: 423,851

[30] Foreign Application Priority Data Dec, I2, [972 Japan 47-124680 [52] US. Cl. 260/889; 260/25 HA; 260/285 B; 260/297 T; 260/297 SQ; 260/336 A0;

[51] Int. Cl .t C08f 29/12; C08f 45/54 {58] Field of Search. 260/888, 889, 25 HA, 29.7. 260/297 T, 297 SQv 33.6, 33.6 AQ. 33.6

P0, 45.7 R, 42.2l, 42.31

June 24, 1975 [56] References Cited UNITED STATES PATENTS 3,498.96} 3/1970 lchikawa et al .v 260/94, 3.74l 93l 6/1973 Martin et a]. .v 260/889 Primary E.raminerMurray Tillman Assistant Examiner-J. Ziegler Attorney, Agent, or FirmLadas Parry, Von Gehr, Goldsmith & Deschamps 57] ABSTRACT 9 Claims, No Drawings ETHYLENE-PROPYLENE TERPOLYMER AND CRYSTALLINE 1,2 POLYBUTADIENE This invention relates to an ethylene-propylene rub ber composition. More particularly, this invention relates to a rubber composition having a high vulcanization rate. a high green strength and an excellent processability. comprising a polybutadiene having a 1.2- addition unit content of at least 70 7( (referred to hereinafter as l,2-polybutadiene) and an ethylenepropylene-diene terpolymer (referred to hereinafter as EPDM).

Commercially available ethylene-propylene rubbers, particularly EPDM are excellent in thermal resistance. ageing resistance, weather resistance and ozone resistance, have good electric properties and good cold brittleness, and are similar to natural rubber particularly in behavior of elastic properties on temperatures. Therefore. the EPDM can be vulcanized with sulfur similarly to conventional rubbers. Further, the EPDM can be produced at considerably low cost as compared with conventional diene rubbers, because the starting materials, ethylene and propylene, for the EPDM are supplied in large amounts and at low cost by petrochemical industry. In addition. the EPDM can be extended with a large amount of oil. Thus, the EPDM is advantageous even in the aspect of economy, and hence, is expected as wide-use rubbers in future. However, the EPDM is greatly disadvantageous in processability, i.e.. the vulcanization rate is very low and the stickiness is low. Therefore, EPDM is greatly limited in practical use.

The present inventors have extensive research on EPDM having no such disadvantages to find that by blending the specific l.2-polybutadiene with the EPDM. the above-mentioned disadvantages of the EPDM are removed, the extrudability of the EPDM is improved, and the rubbery properties of vulcanizate of the EPDM are hardly impaired or rather improved.

An object of this invention is to provide an EPDM composition having improved properties.

A further object of the invention is to provide an EPDM composition having a high vulcanization rate, a high green strength and an excellent processability.

A still further object of the invention is to provide an EPDM composition comprising an EPDM and L2- polybutadiene.

Other objects and advantages of the invention will be apparent from the following description.

According to this invention, there is provided an EPDM composition comprising 97 to 50 by weight of at least one EPDM and 3 to 50 by weight of at least one l,2-polybutadiene having a l.2-addition unit content of at least 70 a crystallinity of at least 5 and an intrinsic viscosity of at least 0.7 dl/g as measured in toluene at 30C.

The l ,2-polybutadienes used in this invention have a l,2-addition unit content of at least 70 preferably at least 85 7 When the 1,2-addition unit content is less than 70 the green strength is too low. Further, the crystallinity of the l,2-polybutadienes is at least 5 preferably 5 to 50 particularly preferably 10 to in view of ease of mixing. When the crystallinity is less than 5 7r. the green strength-improving effect is too small, and the physical properties of the vulcanizate of such a composition are not satisfactory. Furthermore, the 1,2-polybutadienes have an intrinsic viscosity as measured in toluene at 30C of at least 0.7 dl/g, preferably at least 1.0 dl/g. When the intrinsic viscosity is less than 0.7 dl/g, the green strength of the composition is unsatisfactory, and the physical properties of vulcanizate, particularly modulus, are inferior. 1,2- Polybutadienes satisfying the above-mentioned conditions can be produced by the methods disclosed in U.S. Pat. Nos. 3,498,963 and 3,522,332. The above l,2- polybutadienes may be used alone or in admixture of two or more, or in admixture with such an amount of other [,Lpolybutadienes as not to impair the effect of the invention.

In this invention, the amount of the 1,2- polybutadienes used is 3 to 50 by weight based on the weight of the rubber compsotion of this invention. When the amount is more than 50 the composition is not desirable in respects of resilience and permanent set. When the amount is less than 3 by weight. sub stantially no effect of this invention is obtained.

The EPDM used in this invention may be any of those which are commercially available, though those comprising 50 to 80 by weight of ethylene. 50 to 20 by weight of propylene and up to 5 by weight of diene (corresponding to an iodine number of about 50) are preferably used in general. Typical examples of the diene include l,4-hexadiene, dicyclopentadiene, 5- methylene- 2-norbornene, S-ethylidene-Z-norbornene. l,5cyclooctadiene, etc. When the propylene content is less than 30 by weight, the EPDM per se has a great green strength, and in addition. the vulcanization rate and processability of the EPDM are also improved by blending the 1,2-polybutadienes therewith according to this invention. The EPDM may be used alone or in admixture of two or more.

In this invention, the l,2polybutadiene and the EPDM may be mixed by any known method. for example, by mixing a solution of the 1,2polybutadiene with a solution of the EPDM and then removing the solvents from the resulting mixture, or by conventionally mechanically mixing the 1.2-polybutadiene with the EPDM each in the form of solid by means of, for example, rolls, Banburys mixer, kneader-blender. or the like.

It is, of course, possible to incorporate into the rubber composition of this invention at least one conventional compounding ingredient, such as reinforcing agents, fillers, extender oils, pigments, vulcanizing agents, vulcanization accelerators, vulcanization activators, antioxidants, ultraviolet absorbers, blowing agents, odorants, softening agents, etc.

The rubber composition of this invention has a high green strength, a high vulcanization rate and a greatly improved processability, such as high extrusion rate and a high stickiness. Further, the vulcanizate of the rubber composition is greatly excellent in hardness and resistance to crack-growing. In addition. the rubbery properties of the EPDM, for instance, resilience and permanent set, are not so much impaired. Therefore, the rubber composition of this invention can be used as elements which are very useful in industry as novel ethylene-propylene type rubber composition.

The invention is further explained below in more detail referring to the following Examples, which are not by way of limitation, but by way of illustration.

The micro-structures of the l,2-polybutadienes used in the Examples were measured by the infrared absorption spectrum method of D. Morero et al. (Chimie et lnd., 4l 758 l959)). The crystallinity was determined MM... .7- I

by the density measurement method in which the following equation was used:

wherein (1: density of the'specimen measured at C.

(1...: density of the crystalline region.

d,,,,,: density of the amorphous region. 1

X: crystallinity in per cent.

The value of 11 used was that of the crystalline 1.2- polybutadiene calculated by Natta from X-ray experiments to be 0.963 (G. Natta. .l. Polymer Sci.. 20. 251 (1956)). The value of d,,,,, used was 0.892 or the density 1 1n the examples. parts are by weight unless otherwise specified.

EXAMPLE 1 1.2-Po1ybutadiene having a 1.2-addition unit content of92.0 '7(. a crystallinity of 9? and an intrinsic viscos ity of 1.30 dl/g as measured in toluene at C (referred to hereinafter as l.2polybutadiene (A) and an ethylene-propylene-S-ethylidene-Z-norbornene terpolymer rubber having a propylene content of 43 7! by weight and an iodine number of 15 (referred to hereinafter as EPDM (At) were mixed by a Banburys mixer (in the case of vulcanizing system. they were mixed by rolls) with the prescription shown in Table l to prepare 5 rubber compositions.

of the 1.2-po1ybutadiene obtained by the synthesizing process proposed in US. Pat. No. 3.498.963 and found to be completely amorphous by X-ray analysis. The iodine number of the EPDM was determined by the following equation:

1;- (molecular weight) (7: by weight Iodine number The resulting rubber compositions were subjected to measurement of vulcanization rate. green strength. extrusion rate, and die shrinkage. and vulcanizates obtained by vulcanizing the rubber compositions at 160C for 15 min. were subjected to measurement of various physical properties to obtain the results shown in Table (molecular weight) of diene) Table 2 Sample No. Measure l 2 3 4 5 6 men! item Vulcanization Rate (Oscillating disk rheometer) T (minsecl 15'24" 14'12" 13'24" 1242" 11'48 11'12" T9(l-T|U (min. SCCl 10'115" 9'28" 8W2" 7'26" 6'00" 5'28" Green strength (at room temperature) /1 modulus lkg/cm'-') 3.7 5.3 7.0 8.4 13.5 20.0 (Tensile strength (kg/cm) 4.3 5K 7.5 9.6 17.1 29.1 Elongation (7r) 400 390 3K0 380 380 390 (at 40C) 100 71 modulus (kg/cm'-l 2.9 3.1 3.5 4.2 8.0 13.0 Tensile strength (kg/cm 3.7 3.3 3.9 4.8 9.9 17.2 Elongation 410 390 360 370 410 420 (tit 30C) 100 modulus (kg/em'-') 1.1 1.2 1.3 1.6 2.6 3.5 Tensile strength (kgleml 1.5 1.6 1.6 1.9 3.5 4.8 Elongation 7?) 390 360 340 340 330 310 Extrusion test l 1 Extrusion rate (cc/min) 244.0 265.0 290.5 288.0 271.0 Die shrinkage ("/11 41.7 41.5 41.0 41.5 40.3 Physical properties of \uleanizate 300 '7: modulus [kg/cm 131 133 13-1 138 142 Tensile strength lkglcm 183 187 189 I86 166 168 Elongation l7rl 410 420 420 410 370 360 Hardness [.llS Hs) 6) 71 73 74 77 7 Tear strength (kg/em] 49 53 54 54 55 57 Resilience ("/r I 47 42 38 35 27 28 Table 2 Continued Sample No. Measurel 2 4 5 6 meat item Compression permanent set 1%) l8 l8 l8 l ll 25 Crack-growing (2) 500 times 5.3 1X 4.l lllllO times 9.3 4.2 5.7

3000 times 15.4 8.8 9.7

Remarks C ompara- Examples tire Example Note:

(I E\truder conditions crc as follous:

Barrel temperature 7(|( Die temperature. l()5'( Scre rcuilutiun: 2] rpm 12) Numerals shim the lengths of cracks (mm).

EXAMPLE 2 The 1,2-polybutadiene (A) and the EPDM (A) used 2 Table 4 Sample No. 7 8 9 It) I 1 Measurement item vulcanization rate (Oscillating LllSk rheometer] T90 (min. sec) ll'lll)" 8'06 8'06" 7'24" 7'4K" TJO-Tll] (min. See) 6'24" 4'06" 3'48" 3'36" 4'24" Green strength (at room temperature) Tensile strength (kg/cm") 5.3 5.8 5.) 7.0 14.8 Elongation ('34) 190 I20 2H) 200 Ill] (at 50C) Tensile strength (kg/em") 3.5 41) 4.4 4.8 llit) Elongation (7d 42H 33" 300 200 260 (at 80C) Tensile strength (kg/cmfi 1.2 l.2 l.2 l3 L4 Elongation (7%) 47(1 430 360 340 240 Extrusion rate ll) [cc/min) l8(1.3 NBA 302.3 205.6 2l2.5 Remarks Compara Examples tive Example (I l Extrutler conditions ere as folluns:

Barrel temperature: 70C Die temperature: l l()( Screw revolution: 2| rpm.

EXAMPLE 3 in Example I were mixed with the prescription shown in Table 3 by means of a Banburys mixer (in the case 45 0f vulcanizing system, they were mixed by rolls) to obtain rubber compositions.

The l,2-polybutadiene (A) used in Example 1, 1.2-

ample of 1.85 dl/g as measured in toluene at 30C (referred to hereinafter as 1,2-polybutadiene (B)). 1.2- polybutadiene having a l.2-addition unit content of 86.7 /z. a crystallinity of 7r and an intrinsic viscosity These components were mixed with the prescription shown in Table by means of a Banbury's mixer (in the case of ulcanizing system. by means of rolls) to prepare rubber compositions.

Table 5 Sample No. 7 l2 l3 l4 l5 l6 l7 1X 19 20 II 22 23 24 Ingredients blended EPDM (A) (part) 100 90 J0 70 70 70 W EPDM (B) (part) 100 -10 J0 )0 7(1 70 70 l.2-Polybutadiene (A) (part) l0 l0 30 (8) (part) l0 30 l0 30 (X) (part) l0 30 i l0 30 Carbon black (HAF) (part) 67.5 Naphthenic extender oil (Part) Zinc oxide (part) 5 Stearic acid (part) I The same as left Accelerator TS (part) L5 Accelerator M (part) 0.5 Sulfur (part) l .5

Remarks Comp Example Comp. Example Comp. Example Comp. Example Comp.

Ex. Ex. Ex. Ex. Ex.

of 2.05 dl/g as measured in toluene at 30C (hereinafter referred to as 1.2-polybutadiene (X)) for comparison. the EPDM (A) used in Example I and an ethylenepropylene-5ethylidene-2-norbornene terpolymer rubber having a propylene content of 27 71 by weight. and an iodine number of IS (referred to hereinafter as The resulting rubber compositions were subjected to measurement of vulcanization rate. and green strength, and the vulcanizates obtained by vulcanizing the compositions at lC for 30 min. were subjected to measurement of hardness. crack-growth. resilience. and compression permanent set. The results obtained are EPDM (8)) were used in amounts shown in Table 5. 30 shown in Table 6.

Table 6 Sample No. Measurement items 7 Vulcanization rate (Oscillat ing disk rheometer) T90 min. scc) T90-Tl0 (min. sec) Green strength (at room temp.) Tensile strength (kg/cm) Elongation ('7?) 50C) Tensile strength (kg/cm) Elongation (7i 1 all (KWC) Tensile strength (kg/em Elongation ("1%) Physical properties of \uleanizate Hardness (JIS Hs) Crackgrowth" times I000 times |0000 times 70 l 150 l H50 1200 i220 [090 ll.0 1.4 L6

Table 6 Continued Sample No. Measurement items 7 l2 l3 l4 l5 l6 l7 l8 I) It) 21 22 23 24 Resilience (9t) 5t) 36 38 4l 35 36 4l 5X 42 43 45 4U 41 45 Compress ion permunent SLI (70) I6 27 3] 32 3l 33 21 l 24 33 27 30 Remarks Comp. Example Comp, Example Comp. Example Comp, Example Comp.

Ex. x. Ex. Ex. Ex.

Note. Numerals refer to lengths of cracks (mm b. "Totally cracked.

EXAMPLE 4 ness. 100 /r modulus, 300 modulus. tensile strength. lqzpolybumdiene having a lzaddition unit Content tear strength. permanent elongation and compression of 92.0 7: a crystallinity of 24 7: and an intrinsic viscospermanent The results Obtamed are shown m Table ity of 1.57 dl/g as measured in toluene at 30C (re- 20 ferred to hereinafter as l.2-polybutadiene (C)) and an ethylene-propylene-S-ethylidene-2-norbornene ter- T bl 8 polymer rubber having a propylene content of 42 7r by weight and an iodine number of 20 (referred to herein- Example No. after as EPDM (C)) were mixed with the prescription Mcasuremcm 35 36 shown in Table 7 by means ofa Banbury s mixer (in the vulcanization rate case of vulcanizmg system. by means of rolls) to pre- (CURELASTOMETER) T90 (min. sec) l9'll0" 6'45" pare rubber (,Ol'l'lPOSIIlOflS, TQLLTIO (mm Sec) Table 7 Green strength 30 (at room temperature) Tensile strength kg/Cm) 7 l l Sample No. Extrusion rate [cc/min) 293 347 Ingredients blended 25 26 Physic?! pmpemes vulcamzate EPDM (pan) 100 90 Elongation (71) 380 420 LZ-Polybutadiene (Cl (part) 0 l0 figg g gf fig E Carhon hlaclt tHAF) (part) 5 5 300 modulus (kg/emu) 7] 73 lllizlignislum silicate T'Tensile strength (lgcm 93 82 car strength cml 27 33 Nuphlhfimc lender ml (Pan) 2 2 Permanent elongation (7c) 26 25 f (pan) 5 Compression permanent set '7r) 25 23 g i Q Remarks Cnmpara- Example ear C llCI fi Accelgolttor M (part) 3 2 40 Example (wtmmcthyhhiuram Note: The conditions of cxtruder new as follows: i l TRA (pun) Barrel temperature: 70C CCE 8T2} OI D t i Y \J QC (dipentamethylencthiuram T r p m ltetrasulfide) (part) 0.75 0.75 Sulfur (part) L5 L5 Remarks Compara- Example tive EXAMPLE 5 Example The 1,2-p0lyburadtene (A) and an ethylenepropylene-dicyclopentadiene terpolymer rubber having a propy- The resulting rubber compositions were subjected to lene content of 38 by weight and an iodine number measurement of vulcanization rate. green strength and extrusion rate, and the vulcanizates obtained by vulcanizing the rubber compositions at lC for 30 min. were subjected to measurement of elongation, hardof 15 (referred to hereinafter as EPDM (D)) were mixed with the prescription shown in Table 9 by means ofa Banburys mixer (in the case of vulcanizing system, by means of rolls) to prepare rubber compositions.

tive Example l able l 1 Sample No.

ingredients blended 32 l 34 5 R6 37 EPDM (A) lpart) 11m n5 m si no in 1.2-Po1yhutadiene (Y) (part) (I 5 11) 15 7 1.2-Pol \hutatlicne 1].) (part) i i 111 31) Carbon black (HAFI (part) (7.5 1 7.5 07.5 67.5 mi 67.5 Naphthcnic extender oil (part) 35 35 35 35 35 35 Zinc oxide lpart) 5 5 5 5 5 5 Stearic acid lpart) 1 l 1 1 l 1 Accelerator TS lpart) 1.5 1.5 1.5 1.5 1.5 1.5 Accelerator M lpart) (L5 115 11,5 (1.5 (1,5 115 Sulfur lpart) 1.5 1. 1.5 1.5 1.5 1.5

Remarks (omparatiw lawmples The resulting rubber compositions were subjected to measurement of vulcanization rate and green strength to obtain the results shown in Table 11).

COMPARATIVE EXAMPLES LZ-Polybutadiene having a 1.2-addition unit content of 82.5 71. and an intrinsic viscosity of 11.25 dl/g as measured in toluene at C (erystallinity was impossible to measure) (referred to hereinafter as 1.2-po1ybutadiene (Y)) or 1.2-polybutadiene having a 1.2addition unit content of 58.3 7:.acrysta11inity of11% and an intrinsic viscosity of 1.15 dl/g as measured in toluene at 30C (referred to hereinafter as 1,2-polybutadiene (7.)), and the EPDM (A) were mixed with the prescription shown in Table 1 1 by means of rolls to prepare rubber compositions.

The resulting rubber compositions were subjected to measurement of green strength to obtain the results shown in Table 12.

Table 12 Sample No Measurement item 32 33 34 35 36 37 Green strength (at room temperature) Tensilestrength .1) 4.7 4.3 3.8 5.1) 4,8 (kg/cm") Elongation 31K) 4511 521) 681) 2911 2811 ('4) 1at51)() Tcnsilestrength 3.4 2.) 2.7 2.5 3.3 3.11 (kg/cm) Elongation 441) 511) 621) 731) 3 21) 401) /1) (at31lC) Tensile strength 1.3 1.2 1.1) 1.1] 1.2 1.1) (kg/cm Elongation 491) 6011 (i911 7711 451) 421) 1%) Remarks Comparative Examples What is claimed is:

1. An ethylene-propylene rubber composition comprising 3 to 511 by weight of at least one 1.2- polybutadiene having a 1,2-additi0n unit content of at least 70 a crystallinity of at least 5 and an intrinsic viscosity of at least 11.7 dl/g as measured in toluene at 30C, and 97 to 51) by weight of at least one ethylene propylenediene terpolymer rubber.

2. An ethylene-propy1ene rubber composition cording to claim 1, wherein the l.2-polybutadiene a 1.2-addition unit content of at least 3. An ethylene-propylene rubber composition cording to claim 1, wherein the 1.2polybutadiene a crystallinity of 5 to 51) '70.

4. An ethylenepropylene rubber composition cording to claim 1, wherein the 1.2-polybutadiene a erystallinity of 10 to 311 7r.

5. An ethylene-propylene rubber composition cording to claim 1, wherein the 1,2-po1ybutadiene has LtC

has

has

has

an intrinsic viscosity of at least 1.1) (ll/g as measured in toluene at 30C.

8. An ethylene-propylene rubber composition according to claim 1, which further contains at least one compounding ingredient selected from the group consisting of reinforcing agents, fillers, extender oils. pigments vulcanizing agents. vulcanization accelerators. vulcanization activators. antioxidants, ultraviolet absorbers, blowing agents, odorants and softening agents.

9. A vulcanizate of the rubber composition according to claim I. 

1. AN ETHYLENE-PROPYLENE RUBBER COMPOSITION COMPRISING 3 TO 50% BY WEIGHT OF AT LEAST ONE 1,2-POLYBUTADIENE HAVING A 1,2-ADDITION UNIT CONTENT OF AT LEAST 70 % , A CRYSTALLINITY OF AT LEAST 5 % AND AN INTRINSIC VISCOSITY OF AT LEAST 0.7 DL/G AS MEASURED IN TOLUENE AT 30*C, AND 97 TO 50 % BY WEIGHT OF AT LEAST ONE ETHYLENE-PROPYLENEDIENE TERPOLYMER RUBBER.
 2. An ethylene-propylene rubber composition according to claim 1, wherein the 1,2-polybutadiene has a 1,2-addition unit content of at least 85 %.
 3. An ethylene-propylene rubber composition according to claim 1, wherein the 1,2-polybutadiene has a crystallinity of 5 to 50 %.
 4. An ethylene-propylene rubber composition according to claim 1, wherein the 1,2-polybutadiene has a crystallinity of 10 to 30 %.
 5. An ethylene-propylene rubber composition according to claim 1, wherein the 1,2-polybutadiene has an intrinsic viscosity of at least 1.0 dl/g as measured in toluene at 30C.
 6. An ethylene-propylene rubber composition according to claim 1, wherein the 1,2-polybutadiene has a 1,2-addition unit content of at least 85 %, a crystallinity of 10 to 30 % and an intrinsic viscosity of at least 1.0 dl/g as measured in toluene at 30*C.
 7. An ethylene-propylene rubber composition according to claim 1, wherein the terpolymer rubber has an ethylene content of 50 to 80 % by weight, a propylene content of 50 to 20 % by weight and a diene content of up to 5 % by weight.
 8. An ethylene-propylene rubber composition according to claim 1, which further contains at least one compounding ingredient selected from the group consisting of reinforcing agents, fillers, extender oils, pigments, vulcanizing agents, vulcanization accelerators, vulcanization activators, antioxidants, ultraviolet absorbers, blowing agents, odorants and softening agents.
 9. A vulcanizate of the rubber composition according to claim
 1. 